Hot Sauce Festival
I was a regular for about 4 years in a row, and yes, it is worth it. I want to point out, however, that it is more of a salsa festival than a hot sauce festival, from what I have experienced, anyway.
My recommendation is that you come EARLY. Be there when they open. Peruse the sample tables (there are many.) About an hour into it, the festival will start getting crowded. That's okay because by then you've already schmoozed with all the people at the sample tables and gotten all your samples. At that point, you can go around for seconds and decide what to buy. Then buy yourself a margarita, kick back and listen to the bands, and when you're ready, get something to eat. By this time, it should be midday, the sun will be blasting, and unless you have a spot in the shade, you probably won't want to stay too much longer.
I haven't been in about 5 years, but the short answer is yes, its worth an hour drive. I'm assuming since you are considering it, that you are not one who minds waiting in lines (IIRC, they weren't all that long ) in 100 degree heat. I mean it is Austin in August. It'll be hot, but you know, you have to say it. There's lots of hot sauce, beer, music.